Jan 20, 2017· So, when it comes to 5K vs. 4K on your Mac, here's how to choose the right HD display for you! Pixels. 5K means roughly 5000 pixels wide. 4K means roughly 4000 pixels wide. 5K is obviously bigger than 4K — says so right in the name! — but how much bigger? 5K is 5120 x 2880, which works out to 14,745,600 pixels total.